Disease deposits which cause reduction of flow of body fluids in internal body channels occur in various body sites including the arteries, the ureters and the bile ducts. Conventional surgical techniques which are used to remove the obstructive material include operative procedures and minimally invasive procedures. In an operative procedure, skin incision directly exposes the disease site to facilitate removal of diseases. In a minimally invasive procedure, a surgical instrument is inserted percutaneously (through the skin) into a body channel or cavity and advanced to the disease site. The instrument may use various means (e.g. mechanical, chemical, photophysical) to remove the diseased area and restore normal flow.
In various techniques heretofore conceived for using laser energy as a means to remove diseased areas within body channels, the laser energy enters the proximal end of a radiation transfer conduit (e.g. an optical fiber), travels through the fiber and exits from a more distal operative end within the body channel to reach the treatment site. A major difficulty with these prior techniques was in providing adequate means for non-traumatically guiding the operative end of the radiation transfer conduit to the treatment area and then providing a sufficiently efficient means for removing all or a large portion of the diseased obstruction. Body channels may tortuously curve and branch and the radiation transfer conduit must therefore be flexible and yet maneuverable and controllable. Since manpulation of the transfer conduit must be controlled at one end thereof, the conduit must be capable of responsing to both torsional and pushing forces applied to its proximal end. Furthermore, during the obstruction removal process, the radiation transfer conduit must often pass through an area of obstruction to treat more distal areas wherein and beyond a lesion. In some situations, the obstruction may be quite large compared with the size of the beam of laser energy being applied. Therefore, in order to dissolve or reduce such obstructions the beam must be moved or additional treatment means must be utilized to reduce the obstructions after an initial or new channel has been made through the obstruction. Moreover, when any radiation transfer conduit is moved within the body channel, it is essential that its laser energy not be directed at non-contiguous sites within the obstructive deposits, and thereby avoid creating a hazard of embolic events. In addition, the newly created channel must be sufficiently wide to permit adequate re-establishment of the flow of body fluid despite the requirement of using a low profile radiation transfer conduit. Finally, the aforesaid problems were further complicated by specific site factors that often occur at different types of disease areas (e.g. atherosclerosis, uretheral stones, gallstones).
In U.S. Pat. No. 4,641,650 a method is disclosed for destroying atheromatous plaque within an artery of a patient using a catheter system including fiberoptical cable means which includes optical diagnostic means and a treatment fiber optical array means. The diagnostic means is used to sense the presence and location of the plaque in the artery so that the treatment means can be directed on the plaque and avoid damaging healthy tissue. However, despite the improvements in treatment results afforded by the aforesaid sensing system, there existed a need for a more effective system for removing body channel obstructions, and moreover one that was compatible with and could encorporate the sensing system.
Accordingly, a general object of the invention is to provide an improved method of delivering laser energy for the treatment of an area within a body channel or cavity.
Another object of the invention is to teach an improved method and to provide an instrument usable in said method capable of tunneling through a body channel or cavity and of also providing guidance and positioning capabilities that will provide an improved treatment modality in terms of safety and efficacy.
Another object of the invention is to teach an improved method and provide an instrument for enlarging an opening within a body channel or cavity by providing a means to deliver laser energy to contiguous area of diseases and thus diminish the chance of embolic events.
Yet another, more specific object of the invention is to provide an improved instrument of radiation transfer which can be inserted into a body channel having an obstruction and then be controlled to create or enlarge a first opening through the obstructive body channel such that said instrument can advance further through this first channel and thereafter serve as a directional guide for another component of the instrument capable of providing subsequent treatment when operationally interfaced with the diseased site.
Still another object of the present invention is to provide a catheter assembly for removing obstructions from a body channel wherein a first movable guidewire element with radiation capabilities is movable within a second larger catheter body having at least one radiation transfer conduit, so that the first element can be positioned to form an initial opening in the body channel obstruction being treated and then can serve as a guide means to advance the second larger catheter body so that its radiation transfer cnduit can be positioned near the channel obstruction to further dissolve diseased tissue and greatly enlarge the opening through the obstruction.